I have to write equations that have a lot of subscripts. What is the shortcut key in Microsoft Office to write subscripts in equations?

In Office's builtin equation editor you can type You must enter a space after entering. For example,
will give you



For example



I have tried everyone's suggestions, and nothing has worked, but I finally figured out what was going on. I use Word 2013, and write out a lot of tests for math and physical science, which include many formulas with subscripts. However, most of my formulas in physical science use "Normal Text" (text that is not italicized). When you are using Normal Text, the "SHIFT" + "underscore and subscript" + "space" that everyone else had shared does not work. It was only when I clicked on the "Normal Text" setting in the upper left corner of the screen next to the "Equation" dropdown (while in Equation Editor), to turn OFF Normal Text, that the shortcut of "SHIFT" + "_(subscript)" actually worked. So if you are typing an equation that uses regular text instead of italicized text, make sure you have deselected "Normal Text" in the upper left of the screen before attempting to use the shortcut keys for subscripts. Example: To type NaNO3 and make the 3 a subscript, but have the text regular and not italicized, do the following:
The 3 should now be subscripted following the O. You can then click on "abc Normal Text" again to continue typing the equation. Hope this helps. 


If you have to write lots of equation (mostly scientific with some greek symbols etc) than there is hidden shortcut in MS Word which has to be activated manually by user. This method is fantastic and is nicely explained in https://www.youtube.com/playlist?list=PLbTExLDPxtBPTE2fS1MysSqFCkHh1N3 


Any of the answers suggested above did not directly work for me. However, I cracked the problem with a little clarification. 


With Microsoft Word Equation Editor 3.0 or 3.1:
Example: You can find more keyboard shortcuts here. 


*Superscript: Press CTRL+SHIFT+ = *Subscript: Press CTRL+ = Supposedly. I don't have Office so i can't confirm this, but it's what a Google search got me. Let me know if it works! EDIT: apperently for equation manager CTRL+L does subscript while CTRL+H does superscript. Once again. i googled it so it would be awesome if someone could check it out. 


type Alt+=, to start an equation. type V than an underscore and a space, it will display a box in the subscript next to "V" type in anything in the subscript box. For example Vmax. 

